Add .editorconfig file

.editorconfig is a quality of life improvement that helps maintain the
same formatting throughout the files. If you get an extension to
your code editor, it automatically checks and corrects styling in files
upon saving. Some editors even have native support, for more info see
editorconfig.org.

I find this most useful for automatically inserting final newline in the
files as well as for trimming the trailing whitespaces; however; you can
also set indent style (tab vs spaces), indent size, tab width,
enconding, and end of line style (windows vs unix).

Author: adamlazik1

.editorconfig

@@ -0,0 +1,5 @@
+root = true
+
+[*.adoc]
+insert_final_newline = true
+trim_trailing_whitespace = true